The present invention relates generally to apparatus and methods for applying a surface treatment to roadway surfaces and more specifically to a truck mountable surface treatment distributor apparatus and method providing the operator with control of the application rate of the product in real time as the surface treatment is being applied. The present invention also relates to apparatus and methods for cleaning the applicator spray tips so as to easily maintain the spray apparatus and prevent clogging of the applicator apparatus over repeated usage.
Asphalt surface treatments are applied to asphalt roadways and surfaces mainly as a preventative maintenance procedure to prevent or delay degradation of the road surface from environmental exposure to rain, snow, and thermal temperature variations. Surface treatments are also applied to enhance the wearing properties of the roadway and to improve fraction between the vehicle tires and the roadway.
Generally, asphalt surface treatments are composed of a thin layer of asphalt material made from an asphalt emulsion, cutbacks or asphalt cement. Mastics and/or other modifiers may be added to liquid asphaltic mixture and may include rubber, latex, and polymers. Additional additives such as sand, aggregate, fillers and rubber crumbs may applied after the asphaltic mixture is applied to the pavement surface. In other known sealing methodologies, certain seal coats such as slurry seals, utilize aggregates and fillers that are combined in the seal coat mixture prior to application on the asphalt surface.
Asphalt surface treatments are typically applied by a distributor spray system such as a truck mounted system with multiple spray applicators or “spray tips” attached to a spray bar mounted on the rear of the truck. The fluid or surface treatment to be applied to the roadway is stored on a tank mounted to the truck and drawn from the tank through a pump and into the spray bar and shot or emitted as a spray from the spray tip nozzles in a downward direction and on to the road surface. The spray applicators are in fluid communication with a manifold and the pressure within the manifold is controlled by a control panel so that the operator may control and adjust the rate of fluid application to the road surface. However, in most if not all applications, the application of surface treatments to a roadway surface requires intermittent spraying and actuation of the system due to environmental working conditions or to allow for treatment of certain areas of the roadway. For example, during periods of high winds spraying of a roadway surface may result in the surface treatment being blown out of the desired coverage area or being substantially dispersed in the air. As such, it is not cost effective to continue spraying operations until environmental conditions become more favorable spray operations that can change within minutes. As the truck is on site, yet not conducting spray operations, the surface treatment may which is in a liquid state may begin to congeal and thicken resulting in the formation of agglomerated particles into small chunks of hardened material that can result in the partial stoppage and clogging of the spray system and spray applicators. Also, if the spraying system is not cleaned or flushed soon after spraying operations are stopped or completed, the spraying application system and spray applicators may become clogged which substantially reduces the ability to conduct spray operations until the system and equipment are flushed or cleaned at a maintenance facility.